Abstract: In this paper, a method for determination of refractive index in membrane of fuel cell on basis of three-longitudinal-mode laser heterodyne interferometer is presented. The optical path difference between the target and reference paths is fixed and phase shift is then calculated in terms of refractive index shift. The measurement accuracy of this system is limited by nonlinearity erro...

Recent data suggest that a large number of people are blind in different parts of the world due to high refractive error because they are not using appropriate refractive correction. Refractive error as a cause of blindness has been recognized only recently with the increasing use of presenting visual acuity for defining blindness. In addition to blindness due to naturally occurring high refrac...

These include: References http://bjo.bmjjournals.com/cgi/content/full/90/5/521#BIBL This article cites 27 articles, 14 of which can be accessed free at: Rapid responses http://bjo.bmjjournals.com/cgi/eletter-submit/90/5/521 You can respond to this article at: service Email alerting top right corner of the article Receive free email alerts when new articles cite this article sign up in the box a...

conclusions based on our study, the prevalence of myopia is more than other types of refractive error, which is similar to that reported in previous studies on other school-age populations in some asian countries. the high prevalence of refractive error among school-age children indicated that untreated refractive error is one of the most common public health problems. patients and methods in t...

purpose: to determine the prevalence of uncorrected refractive errors and its determinants in tehran in 2002. methods: a total of 6497 citizens representing a cross-section of the population of tehran were sampled using a stratified random cluster sampling strategy. of these, 4565 (70.3%) subjects participated in the study and were transferred to a clinic for an extensive eye examination and in...